The default values of both are 15 minutes, which means I have to re-login very often. So I always change it to 60. But I have been aware since long time ago, that when they are set to 60, I almost don't need to relog.

For example, last night I went to sleep without shutting down my computer, and I was on the back-end page before going to bed. But this morning I can do anything without having to go back to login page.

Why is this happening?

Technically, shouldn't the session only last 60 minutes?
And I suppose this is for all users. My website doesn't have any other user at the moment, but I'd like to know, how to set this only for the Super User?